What are Coccidiosis?
Any species of bird can be susceptible to the coccidian parasite, which can be found worldwide. Most species of coccidia have a direct life cycle. Non-infective oocysts, or eggs, are passed in the feces of infected birds into the environment. Here, they develop into an infective form, or a sporulated oocyst. A healthy bird can ingest this form from contaminated feed or water. The infective oocysts then invade the intestines of the bird, where they undergo several more stages of development until they become sexually mature parasites. These parasites then lay eggs, which are passed out with the feces. This life cycle is generally completed in a span of 1 to 2 weeks.
Coccidiosis, also referred to as intestinal coccidiosis or coccidiasis, is caused by the protozoan parasite in the Eimeriidae family. While poultry, game birds, pigeons, and doves are most commonly affected, coccidia eggs have been found occasionally in parrots, canaries, finches, lories, and budgerigars. This parasite usually invades part or all of the intestinal tract in birds, but has been found in other organs, such as the kidneys and liver.
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Symptoms of Coccidiosis in Birds
Symptoms of coccidiosis mainly involve the digestive system. As the coccidia replicate, tissue damage that results can cause disruptions in normal digestive and absorption processes, as well as feeding habits. Rapid weight loss can occur, which can lead to severely infected birds that may become susceptible to other diseases and infections. Birds can also be infected without any visible symptoms. Signs can include:
- Severe diarrhea that can be watery, bloody, or contain greenish mucus
- Loss of appetite
- Weight loss
- Decreased thirst
- Decreased growth rate in young birds
- Development of culls
- Decreased egg production
- Ruffled feathers
- Depigmentation or pale skin
- Secondary infection from another infectious agent
There are two types of coccidiosis seen in birds.
- Coccidiosis refers to a parasitic infection that produces visible symptoms
- Coccidiasis refers to an infection that is present without any symptoms
Causes of Coccidiosis in Birds
Coccidiosis in birds is caused by an infection of the coccidia parasite. The coccidia oocysts are transmitted from bird to bird by ingestion of contaminated matter. This can occur from:
- Infected droppings
- Contaminated food or water
- Contaminated soil, dust, or litter
- Exposure to contaminated insects or animals
- Contamination through carriers, such as human handlers, equipment, or clothing
Both infected and recovering birds can shed oocysts in their droppings, even if they present no visible symptoms of an infection. The oocyst has a hard shell that allows it to survive in the environment for a long time, although they are not infective until they sporulate. This development into an infective stage generally takes 1 to 2 days after they are passed from the feces into the environment.
Diagnosis of Coccidiosis in Birds
Diagnosis will take into consideration your bird’s feed intake, visible symptoms, the appearance and health of any other birds in the population, and growth rates of younger birds, but is dependent on the presence of oocysts in your bird’s feces. Oocysts can be detected through fecal examinations that include fecal smears and fecal flotations. Scrapings from the intestinal tract can also detect oocysts. Further testing can be conducted to determine the species of coccidia that is infecting your bird, and can include a PCR test. The presence of lesions, most commonly in the intestinal tract, can confirm a diagnosis of coccidiosis.
Treatment of Coccidiosis in Birds
The treatment of coccidiosis will include drug administration to kill the parasites and oocysts, and measures to control transmission and re-infection.
There are a range of anticoccidial drugs that can treat a coccidian invasion in many ways. Some drugs will arrest coccidia growth, while others may inhibit mitochondrial energy production. Amprolium can be used as an antagonist of thiamine, a vitamin needed by the coccidia. Folic acid antagonists and arsenic compounds can also be used. Your veterinarian will determine which drug is appropriate for your bird and the severity of the infection, and will notify you of the risks for that particular drug. Often, medicine is given in water or feed for up to 2 weeks, and may need to be repeated. Resistance to drugs can occur, and your veterinarian may change the medication after so many weeks if your bird needs to be treated for a longer period of time.
Feed may also be medicated continuously up to the first eight weeks of life to prevent an early infection which can be deadly. Antibiotics may be used to treat any secondary infections, and vitamins A and K may be administered to improve health and recovery.
Your bird may develop a natural immunity to coccidiosis during treatment. Immunity can also develop in response to a long term infection. Older birds tend to be more resistant than younger ones, as they have usually been exposed to the parasite at a young age.
Vaccines can be given that consist of live, sporulated oocysts, more often to very young birds to help develop this immunity, but a repeated exposure to the parasite is needed to continue the development of the immunity.
While pet and captive birds can be treated, the infection is usually not eliminated and is only controlled. Measures need to be taken to prevent transmission of this parasite to other birds. While the oocysts are resistant to some disinfects, they can be killed by extreme hot or cold temperatures. Birds can still shed oocysts after treatment and should be separated from healthy birds to reduce transmission.
Cages should be cleaned and disinfected daily to remove any oocysts from your bird’s environment. If you have many birds in your population, separating them, or dispersing them over a larger area can help to reduce the risk of spreading the parasite.
Recovery of Coccidiosis in Birds
Your bird may develop an immunity to the coccidia parasite and can recover, though it may become reinfected. A severe infection can lead to a quick fatality. If your bird has survived a severe infection, recovery can occur within 2 weeks of treatment, but may result in permanent damage.
Prevent this possibly fatal infection through good sanitation and environmental conditions. These can include:
- Adding anticoccidial drugs to feed during the first weeks of your bird’s life
- Avoiding overcrowding your birds
- Providing good sanitation
- Ensuring there is always clean water and feed available
- Separating birds from droppings
- Administering vaccines
- Routinely clean cages or aviary
- Frequently check droppings for oocysts
- Quarantining new birds until deemed healthy